Various products require media feeders for different types of media to be processed by a paper handling system. Media feeders for envelopes, sheets, inserts and the like are used in various equipment, such as folders, inserters, printers and copiers. A common problem in feeders for equipment of this type is a high fault rate in feeding media. This is because the adjustment of the media side guides is often highly dependent on operator skill in making the required adjustment. If the operator sets the side guides too tight, mis-feeds frequently occur. The setting of side guides too tight against the stack of media can also cause the erratic performance in the stack elevator mechanisms used for moving the media to be in engagement with the singulator and feeder mechanisms.
If the operator sets the side guides too loose, then the envelopes can skew and become offset while they are being fed. This can create errors in printing registration and folding operations, as well as jams in the equipment and other related problems. For some feeders, when the side guides are set too loose, the rate of multi-feeding may increase. Incorrectly setting side guides results in higher rates of many types of machine faults and shutdowns. Operators often gain experience in setting the side guides by trial and error; however, having experienced operators are often more highly paid, which can increase the cost of operating the equipment, particularly high speed equipment where there may be frequent need for replenishing the media, as for example, on high speed copiers, laser printers, addressing machines and other types of imaging and office equipment. In situations where experienced operators move on to other jobs and are replaced by inexperienced operators, the inexperienced operator must acquire the knowledge and skill required for optimal adjustments to feeder side guides. Often this process is again accomplished by trial and error, resulting in unsatisfactory performance of the feeder until the operator obtains the requisite skill in adjusting the side guides. These problems occur in both center registered and also in edge registered type media feeders. For typical media processing systems, when the media is center registered, both side guides are adjusted. When the media is edge registered, typically only one side guide is adjusted.
Various techniques have been provided to help assist operators in setting the adjustment. For example, with well-controlled known standard sizes, such as 8½×11 (letter), 8½×14 (legal) size sheets, as well as other size sheets, detents have been provided in assisting in setting the side guides. While the tolerances of standard cut sheet letter size media is typically quite reliable with a tolerance of +/−0.5 mm. However, the size tolerances for envelopes, inserts and pre-printed sheet media are often not as accurate and can be unpredictable, frequently having variations of +/−2-3 mm. Accordingly, the provision of detent-type solutions in positioning the side guides for media of this type will not be satisfactory because of the high tolerances in the media dimensions. For example, if a detent is designed to locate the side guide for an average envelope size, and envelope having a tolerance on the large side of nominal could be compressed by 3 mm, which will significantly increase the rate of mis-feeds. Alternatively, if the detent is located at the maximum tolerance to accommodate the envelopes with the largest positive tolerance, when envelopes with the largest negative tolerance are loaded, it will result in a gap of 6 mm between the stack of envelopes and the side guide. This large gap will result in a significantly higher number of skewed feeds, which can increase the number of jams and other types of faults downstream in the process. Besides jams, some typical faults associated with skewed feeds include misaligned images on the media in the case of a printing system, or increased insertion faults in the case of an insertion system. In cases such as this, at times various operator aids to set the side guides are employed such that the gap between the side guides and the edge of the material is appropriately adjusted. In some systems, in order to compensate for the lack of operator skills in adjusting feeder side guides, expensive mechanisms are added to de-skew the envelope, and sometimes to re-center the envelope before moving it down stream for printing or insertion.
In high capacity feeders that typically employ an elevator mechanism, the problem is compounded. The operator often may load the feeder tray in several steps. The operator frequently loads several handfuls or reams of media in discrete steps. In such a situation, each handful loaded may not be perfectly aligned with the previously loaded handful. Batches of the media in the stack can thus be slightly offset from other batches loaded into the feeder. Also, the entire stack can be slightly skewed between the side guides. If the operator moves the side guides tightly against the edges of the media after the stack of media has been loaded into the feeder in order to push all individual batches toward the center until the edges are aligned, this may correct the situation. But, often, as a result, this operator action to correct the misalignment of the stack often leads the side guides being set too snug against the edges of the stack. This can cause mis-feed failures or elevator mechanism failures. A similar type of problem also occurs in low capacity feeders in which a single handful or ream of media may be loaded in the feeder if the media is not placed perfectly centered between the side guides. In such case the operator may use the adjustment of the side guides to center the stack, which results in a similar type of problem noted above in connection with high capacity media feeders, where the guides are too snug against the edge of the stack.
The problem of adjusting the media guides has been noted in U.S. Pat. No. 6,793,215B2 for “Self-Adjusting Side Guide in Mail Handling Device.” The patent discloses a self-adjusting guide, which is provided for a document-handling machine having a feed deck along which documents are transported. The self-adjusting side guide includes a member mounted for movement along the feed deck toward and away from the documents. A side guide self-adjusts to correct the drag effect problem.